Process for producing cellulose products.



UNITED STATES PATE OFFICE.

EMIL BRONNERT,'OF NIEDERMORSCHWEILER, NEAR Mfi'LHAUSEN, AND MAX FBEMERY, OF OBEBBRUGH, GERMANY.

PROCESS FOR PRODUCTNG CELLULO SE PRODUCTS.

No Drawing.

To allwlwm it may concern:

Be it known that we, EMIL BRONNERT, a subject of the Emperor of Germany, residing at Niedermorschweiler, near Miilhausen, in-Alsace, Germany, and MAX FREMERY, a subject of the King of Prussia, residing in Oberbruch, Germany, have invented a certain new and Improved Process for Producing Cellulose Products, of which the following is a specification.

Cellulose threads have previously been produced by spinning a cuprammonialcellulose solution into acaustic soda bath to precipitate'the cellulose and subsequently eliminating the copper from the threads after a preliminary washing of the latter to remove the soda and ammonia. The threads were. then dried under tension in the usual man- For certain purposes the copper cellulose threads could be dried directly, but care has'always been necessary to avoid the decomposition of the cellulose with resulting injury to the strength of the threads. This old process produces a thread containing cellulose and copper in simple molecular proportion. We have now discovered that a thread containing much less copper, (to one molecule of cellulose, but two-thirds or even only one-half a molecule of copper) may be obtained by the use of a precipitating bath of novel composition and action, namely one which not only precipitates the cellulose by the use of the customary caustic soda, but also contains a substance which combines with and separates out at least portion of the copper in the precipitated cellulose filament.

Among suitable substances for the last mentioned purpose may be mentioned lucose, saccharose, lactose and their equivalents. A suitable quantity of one of these substances, preferably saccharose, is added to a precipitating bath containing the usual quantity of caustic soda. The bath may for example contain 32 grams of caustic soda, and 8 grams of saccharose to each 100 cubic centimeters of water. The jet of cuprammo nia cellulose solution which is spun into this bath is at once precipitated or coagulated, by the action of the soda. A part of the copper of the so formed filament being substituted by sodium and saccharose, the ammonia is eliminated, part of the copper is at once dissolved and precipitated under the reducing action of the sugar in the pres- Specification of Letters Patent.

Application filed December 24, 1907. Serial No. 407,972.

Patented June 18, 1912.

ence of alkali (soda) preferably at the temperature (approximately 45 C. to 70 C.) at which the process is carried on. The precipitating bath is rapidly colored brickred by the suspended cuprous oxid so that any threads that happen to tear off are readily discovered. V These filaments coming from the precipitating bat-h comprise cu- .pric-cellulose or a cupric-sodic-cellulose compound. After having been washed in the usual. manner to remove the caustic soda,

is also washed out, the threads which are of a malachite green of fine transparent brilliancy, may be directly and quickly dried under tension at atemperature'of even 100 C. The remaining copper is withdrawnat any time from the dry threads by washing with diluted (6. g 2%) sulfuric acid.

It will be seen that the action of the saccharose is not that of a precipitant, for whlch purpose it has been previously pro- "during which much of the dissolved copper posed, although it is practically impossible to produce a filament in a saccharose or similar solution however concentrated it may be. The saccharose plays a very different part, namely it combines with portion of the copperto form a substance which is dissolved out of the thread and reduced at once by the hot alkaline bath. It has also been proposed to use a dilute sulfuric acid precipitating bath to which is added sugar or glucose or glycerin to arrest the injurious action of the acid upon the filament. But this in no way suggests the present bath in which no acid is employed and in which consequently there is no noxious acid action to prevent. Moreover the threads produced are of entirely distinct chemical composition-the hydrocellulose of the acid bath being neither as strong-as nor in any way as desirable as the cupric cellulose thread obtained by the present process. Furthermore, the proposal to use an alkaline glycerin precipitating bath, which has been made, has not been of any value, since it was not understood that glycerin per se is not a coagulantand is useless unless the bath contain soda in-suilicient strength to efi'ect the precipitation of the cellulose in the manner described.

Filaments similar to those produced by the present process, having only a low copper content, have never previousl been produced with a soda precipitating ath.

lulose products from cuprammonium latter in suitable form into a precipitating bath containing caustic soda as the precipitant and a sacchariferoussubstance which combines with at least portion of the copin the precipitated cellulose per .present which is carthread to form a compound,

ried away fromthe thread. and then imme-' diately reduced in the presence of soda in the alkaline bath, substantially as described. 2. In the process of manufacturing clelso utions of cellulose, the introduction of the latter in suitable form into a precipitating bath having a temperature of from 45 C. to 75 C. and containing caustic soda as the precipitant and a sacchariferous substance which combines with at least portion of the copper present in the precipitated cellulose thread to form a compound carried away from the ,thread and then immediately reduced in the presence of soda in the bath, substantially as described.

- 3. In the process of manufacturing cellulose products from cuprammonium solutions of cellulose, the introduction of the latter in suitable form into a precipitating bath containing caustic soda as the precipitant and asacchariferous substance which combines with at leastportion of the copper present in the precipitated cellulose thread to form a compound carried away from the thread and then immediately reduced' in the presence of'soda in the bath, and thereafter washing the thread to remove the soda and then drying under tension.

4. In the process of manufacturing cellulose-products from cuprammonium solutions of cellulose, the introduction of the latter in suitable form into a precipitating bath containing caustic soda as the precipitant and a sacchariferous substance which combines with at least portion of the copper present in the precipitated cellulose thread to form a compound dissolved out from the thread and then immediately reduced in the presence of soda in the bath, and thereafter Washing the thread to remove the soda and then eliminating the remaining copper and sugar from the thread tension.

5. A filament of the character described, precipitated from a cuprammonium solution of cellulose by introduction into a bath of caustic soda containing sugar and having its copper content subsequently removed, substantially as described.

In testimo ny whereof We have signed our names to this specification, in the presence of two subscribing witnesses.

EMIL BRONNERT. MAX FREMERY. Witnesses:

Orro KoNm, \VlLHELM FRIEDERICHS.

by washing in dilute (say 2%) sulfuric acid and drying under' 

